to find out what finish is do the following, on an inconspicuous spot like the back of a leg:
1) dip cotton swab in denatured alcohol (not isopropyl alcohol from a medicine chest). If finish becomes sticky or comes off, it's shellac
2) dip new cotton swab in lacquer thinner. If finish becomes sticky or comes off, it's lacquer.
To strip, use a product with methyl chloride in a well ventilated area with eye and skin protection
Bob "Boardman" Borders